Optical interconnection assemblies and systems for high-speed data-rate optical transport systems

ABSTRACT

Fiber optic assemblies and systems for high-speed data-rate optical transport systems are disclosed that allow for optically interconnecting active assemblies to a trunk cable in a polarization-preserving manner. The fiber optic assembly includes at least first and second multifiber connectors each having respective pluralities of first and second ports that define respective pluralities of at least first and second groups of at least two ports each. The first and second multifiber connectors are capable of being disposed so that the at least first and second groups of ports are located on respective termination sides of each ferrule. The fiber optic assembly also has a plurality of optical fibers that connect the first and second ports according to a pairings method that maintains polarity between transmit and receive ports of respective active assemblies. At least one of the first and second groups are optically connected without flipping the fibers, and at least one of the first and second groups are optically connected by flipping the fibers.

TECHNICAL FIELD

The present disclosure relates to optical fiber networks, and inparticular to optical interconnection methods for high-speed data-rateoptical transport systems that use multifiber connectors.

BACKGROUND ART

Some conventional optical fiber networking solutions for high-speeddata-rate optical transport systems utilize 12-fiber (12f) connectorassemblies and often have a point to point configuration. Theconservation of fiber polarity (i.e., the matching of transmit andreceive functions for a given fiber) is addressed by flipping fibers inone end of the assembly just before entering the connector in an epoxyplug, or by providing “A” and “B” type break-out modules where the fiberis flipped in the “B” module and “straight” in the “A” module. Polaritypreserving optical interconnection assemblies that provide fiber opticinterconnection solutions for multifiber connectors in a networkenvironment are discussed in U.S. Pat. Nos. 6,758,600 and 6,869,227,which patents are assigned to the present assignee or its affiliate andwhich patents are incorporated by reference herein.

Storage Area Networks (SANs) utilize SAN directors having high-densityinput/output (“I/O”) interfaces called “line cards.” Line cards holdmultiple optical active assemblies such as transceivers that convertoptical signals to electrical signals and vice versa. The line cardshave connectors with transmit ports {0T, 01T, 02T, . . . } and receiveports {0R, 01R, 02R, . . . } into which network cabling is plugged. Thenumber of ports per line card can generally vary, e.g., 16-, 24- 32- and48-port line cards are available.

For high-speed data-rate optical transport systems, such as 100 gigabit(100 G) optical fiber networks, one of the anticipated line-cardconnector interfaces is a 24-fiber multi-fiber push-on (MPO) connector,such as an MTP® connector. This is potentially problematic becauseexisting network systems and some planned for high-speed data-rateoptical transport systems are based on 12-fiber MPO connectors.Likewise, if 24-fiber trunk connections are implemented, 24-fiber to24-fiber patch cords that provide a connection that maintains fiberpolarity between active assemblies such as transceivers would facilitatehigh-speed data-rate optical transport systems implementation.

SUMMARY

An exemplary aspect of the disclosure is a fiber optic assembly for ahigh-speed data-rate optical transport system. The assembly includes atleast first and second multifiber ferrules, with each multifiber ferrulehaving a mating face for mating to another mating face of an opticalconnector, and a termination face for receiving optical fiber. Eachferrule has a plurality of optical fiber receiving areas that arearranged in at least first and second groups of two or more fiberreceiving areas. The fiber receiving areas of each ferrule have fiberreceiving holes formed in each ferrule, the holes extending from themating face to the termination face so that each the holes areassociated with the at least first and second groups. Respective ends ofthe optical fibers are optically secured in at least some of the holesof each of the first and second groups. The fibers form respectivegroups of optical fibers that optically interconnect the fiber receivingareas from the termination side of the first ferrule to the terminationside of the second ferrule. Some of the optical fibers extend from thefirst ferrule to the second ferrule in a direct orientation so that thefiber receiving areas of each ferrule are optically interconnectedwithout flipping the fibers. Some of the optical fibers extend from thefirst ferrule to the second ferrule such that the optical fibers areflipped so that the orientation of the ends of the optical fibers isreversed as the fibers extend from the first ferrule to the secondferrule.

Another exemplary aspect of the disclosure is a fiber optic assembly fora high-speed data-rate optical transport system having active assemblieseach with transmit and receive ports. The fiber optic assembly includesat least first and second multifiber connectors each having respectivepluralities of first and second ports that define respective pluralitiesof at least first and second groups of at least two ports each. Thefirst and second multifiber connectors are capable of being disposed sothat the at least first and second groups of ports are located onrespective termination sides of each ferrule. The fiber optic assemblyalso includes a plurality of optical fibers that connect the first andsecond ports according to a pairings method that maintains polaritybetween the transmit and receive ports of the active assemblies. Atleast one of the first and second groups are optically connected withoutflipping the fibers, and at least one of the first and second groups areoptically connected by flipping the fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a prior art twenty-four-fiber (24f)fiber optic “trunk” cable having two connectors with “key up”configurations;

FIG. 2 is a schematic diagram similar to FIG. 1, but further includingtwo 24f connectors associated with system active assemblies (not shown),illustrating how the system as shown fails to provide a connectionhaving the proper transmit/receive polarity between the activeassemblies;

FIG. 3 is a schematic diagram of an example embodiment of an examplehigh-speed data-rate optical transport systems that includes two 24f

2×12f optical fiber interconnection assemblies in the form of patchcords;

FIG. 4 is a perspective view of an example coiled 24f

2×12f patch-cord optical fiber interconnection assembly;

FIG. 5 is a schematic diagram of the system of FIG. 3, illustrating thevarious connector ports in more detail;

FIG. 6 shows example harness configurations for the system of FIG. 5 forthe 24f

2×12f assemblies;

FIG. 7 is a perspective view of a 24f

2×12f optical fiber interconnection assembly illustrating an example ofhow the optical fibers of the harness are routed in three-dimensions;

FIG. 8 is an end-on view of active-assembly-wise 24f connector of anoptical fiber interconnection assembly illustrating how the connectorports can be divided up into different groups;

FIG. 9 is an end-on view of cable-wise 2×24f connectors of an opticalfiber interconnection assembly illustrating how the connector ports canbe divided up into different groups;

FIG. 10 is an end-on, key-up view of the active-assembly-wise 24fconnector of an optical fiber interconnection assembly, showing anexample of how the fibers in the top and bottom rows run left to rightaccording to the color code Blue, Orange . . . Aqua, i.e., “B→A”;

FIG. 11 shows a schematic representation of the refractive index profileof a cross-section of the glass portion of an embodiment of a multimodeoptical fiber;

FIG. 12 is a schematic representation (not to scale) of across-sectional view of the optical fiber of FIG. 11;

FIG. 13 is a schematic diagram of a high-speed data-rate opticaltransport system similar to that of FIG. 3, but that utilizes a 24ffiber optic cable and 24f patch cords;

FIG. 14 is similar to FIG. 5, but represents the system of FIG. 13;

FIG. 15 is a perspective view similar to FIG. 7, except for the case ofa 24f

24f optical fiber interconnection assembly;

FIG. 16 and FIG. 17 are end-on views of the assembly-wise and cable-wise24f connectors of the 24f

24f optical fiber interconnection assembly, illustrating how theconnector ports can be divided up into different groups;

FIG. 18 is a schematic diagram of a generalized 12f interconnectionsystem in the process of being interconnected, where the system includestwo 12f

12f optical interconnection assemblies;

FIG. 19 is a schematic diagram of a high-speed data-rate opticaltransport system that includes two 24f

24f optical interconnection assemblies and active assemblies havingtwenty-four single-fiber ports; and

FIG. 20 is a perspective view of an example modular 24f

2×12f optical interconnection assembly;

It is to be understood that both the foregoing general description andthe following detailed description present embodiments of thedisclosure, and are intended to provide an overview or framework forunderstanding the disclosure as it is claimed. The accompanying drawingsare included to provide a further understanding of the disclosure, andare incorporated into and constitute a part of this specification. Thedrawings are not necessarily to scale.

DETAILED DESCRIPTION

Reference is now made in detail to the embodiments of the disclosure,examples of which are illustrated in the accompanying drawings. Wheneverpossible, like or similar reference numerals are used throughout thedrawings to refer to like or similar parts. The letters “L” and “R” inthe reference numbers denote “left” and “right” to distinguish betweenthe same or like parts in different sections of an apparatus, system,assembly or network, and are used in the same manner as “first” and“second” and thus are not intended as being limiting as to position.

It should be understood that the embodiments disclosed herein are merelyexamples, each incorporating certain benefits of the present disclosure.Various modifications and alterations may be made to the followingexamples within the scope of the present disclosure, and aspects of thedifferent examples may be mixed in different ways to achieve yet furtherexamples. Accordingly, the scope of the disclosure is to be understoodfrom the entirety of the present disclosure, in view of but not limitedto the embodiments described herein.

An aspect of the present disclosure is directed to optical fiberinterconnection (or “conversion”) assemblies configured to convert orotherwise interconnect multifiber connectors. Multifiber connectorsconsidered herein by way of example are twenty-four-fiber (“24f”)connectors and twelve-fiber (“12f”) connectors. In an exampleembodiment, the multifiber connectors comprise multifiber ferrules. Theferrules each have a mating face for mating to another optical fiberconnector and a termination side for connection to optical fibers of anoptical fiber cable. One example optical fiber interconnection assemblyis configured to connect a 24f connector having twenty-four ports to two12f connectors each having twelve ports. This interconnection assemblyis referred to generally as a “24f

2×12f assembly.” Another example optical fiber interconnection assemblyis configured to convert or otherwise interconnect one 24f connector toanother 24f connector. This interconnection assembly is referred togenerally as a “24f

24f assembly.”

The optical interconnection assemblies of the present disclosure can beembodied in a variety of different forms, such as an individually formedenclosure with one or more walls in module form (e.g., a stamped-formedmetal box), a flexible substrate with optical fibers associatedtherewith, a cable section, as an optical fiber harness or bundles ofarrayed optical fibers and connectors, as an optical fiber patch cord,or in fiber-optic cabling generally. The interconnection assemblies caninclude combinations of the foregoing. Aspects of the disclosure includecable systems that use the interconnection assemblies described herein.

The term “harness” as used herein means a collection of optical fibers,including fibers bound in groups or sub-groups as by a wrapping,adhesive, tying elements, or other suitable collecting fixtures orassemblies, or fibers that are unbound, for example, loose opticalfibers without tying elements. The harness fibers may be arranged in theform of optical fiber ribbons, and the optical fiber ribbons arecollected together by one or more tying elements or enclosed in asection of fiber optic cable.

The term “patch cord” as used herein is a collection of one or moreoptical fibers having a relatively short length (e.g., 2-4 meters),connectors at both ends, and that is typically used to provide forfront-panel interconnections within an electronics rack, optical crossconnect, or fiber distribution frame (FDF).

The term “trunk” means a fiber optic cable that carries multiple opticalfibers (typically 4 to 96 fibers) and that connects assemblies overdistances longer than that associated with patch cords, such as betweenelectronics racks, rooms, buildings, central offices, or like sectionsof a network.

The term “port” is a fiber receiving area, i.e., a place where anoptical fiber can be inserted or connected to another optical fiber.

Example multifiber connectors used in the assemblies and cablesdescribed below are epoxy and polish compatible MPO or MTP® connectors,for example, part of Corning Cable Systems' LANScape® connector solutionset. Such connectors provide a very high fiber density and containmultiple optical paths arranged in a generally planar array. The opticalpaths are immediately adjacent to at least one other optical path foroptical alignment with the optical fibers in an optical fiber cable. Themultifiber connectors are designed for multi-mode or single-modeapplications, and use a push/pull design for easy mating and removal.The multifiber connectors considered herein can be the same size as aconventional SC connector, but provide greater (e.g., 12×) fiberdensity, advantageously saving cost and space. Multifiber connectors caninclude a key for proper orientation for registration with any requiredoptical adapters. The key can be configured as “key up” or “key down.”Certain multifiber connectors such as MTP connectors may also includeguide pins and guide holes that serve to align the optical fibers whenthe two connectors are engaged.

An optical connector adapter (not shown) may be used to manage the fiberconnections. However, other connection schemes can be used, such as aribbon fan-out kit.

In the discussion below and in the claims, the notation A

B denotes connecting A to B. Likewise, the notation {a1, b1, c1 . . . }{

a2, b2, c2 . . . } denotes connecting a1 to a2, b1 to b2, c1 to c2, etc.Also, the notation n≦p, q≦m is shorthand for n≦p≦m and n≦q≦m.

The assemblies, systems and methods described herein are directedgenerally to high-speed data-rate optical transport systems, e.g.,systems that can optically transport information at rates such asbetween 10 gigabits (10 G) and 120 G. In a typical high-speed data-rateoptical transport system, there are multiple channels, with each channelcapable of supporting a select data rate, with the overall data ratedetermined by the data rate of the channels multiplied by the number ofchannels used. For example, a typical channel for a high-speed data-rateoptical transport system can support 10 G communication, so for atwelve-channel system, the communication data rate can be adjusted inmultiples of 10 G from 10 G to 120 G. With the addition of morechannels, or different data rates per channels, other data rates areobtained. Thus, there is a range of options for the particular systemdata rate, with 40 G and 100 G being possibilities.

FIG. 1 is a schematic diagram of a fiber optic cable 10 in the form of a24f trunk cable (“24f trunk”) having two multifiber connectors 20, e.g.,right and left connectors 20R and 20L. Each connector 20 has ports 22arranged in two rows of twelve and that are color-coded usingindustry-accepted color-coding scheme {B, O, G, Br, S, W, R, Bk, Y, V,Ro, A}={Blue, Orange, Green, Brown, Slate, White, Red, Black, Yellow,Violet, Rose and Aqua}. The direction of the color-coding scheme isindicated in FIG. 1 (as well as in FIG. 2) by the notation “B→A”. Ports22 are connected by corresponding color-coded optical fiber sections(“fibers”) 36, with only two fibers being shown for the sake ofillustration.

Connectors 20 have keys 32, and the two connectors 20L and 20R areconfigured “key up to key up.” Fiber optic cable 10 is configured “keyup to key up,” so that the top and bottom rows of each connector 20 arerespectively connected to their matching color-coded port 22 via fibers36. Where necessary, individual fibers 36 are identified as 36-1, 36-2,etc. Connectors 20R and 20L have respective ports 22L and 22R.

FIG. 2 is a schematic diagram similar to FIG. 1, but further includingtwo active assembly connectors 41 (e.g., 41R and 41L) associated withrespective active assemblies (not shown), such as transceivers. Activeassembly connectors 41L and 41R are arranged adjacent respective leftand right connectors 20L and 20R. In one example, active assemblyconnectors 41 are or otherwise include medium dependent interface (MDI)connectors. Active assembly connectors 41 have ports 42. The upper rowof twelve active assembly ports 42 are receive ports {0R, 1R, . . .11R}, while the lower row of active assembly ports 42 are transmit ports{0T, 1T, . . . 11T}. Active assembly connectors 41 are by necessityarranged “key down” so that they can mate with the respective “key up”fiber optic cable connectors 20. The color-coding is thus A→B left toright. However, this configuration prevents fiber optic cable connectors20 from patching directly into active assembly connectors 41 because thepolarity of the connections between the transmit and receive ports ofthe active assembly connectors will not be maintained. A similar problemarises when trying to use a fiber optic cable 10 having two 12f cablesections and two 12f connectors at each cable end.

High-Speed Data-Rate Optical Transport System with 24f

2×12f Interconnections

FIG. 3 is a schematic diagram of an example embodiment of an examplehigh-speed data-rate optical transport system (“system”) 100 thatincludes two example 24f

2×12f assemblies 110. System 100 includes respective active assemblies40 with the aforementioned connectors 41, and a fiber optic cable 10having two 12f cable sections 11A and 11B each terminated at theirrespective ends by multifiber connectors 20A and 20B having respectivetwelve ports 22A and 22B. System 100 may be, for example, part of anoptical fiber network, such as a LAN or a SAN at an opticaltelecommunications data center. An example active assembly is atransceiver, such as multichannel, high-data-rate (e.g., 10 G/channel)transceiver.

System 100 includes first and second 24f

2×12f assemblies 110L and 110R shown by way of example in the form ofpatch cords (also referred to hereinafter as “patch cord 110L” and“patch cord 110R”, or more generally as “patch cord 110”) that eachconnect the two 12f cable sections 11A and 11B to their respectiveactive assembly connectors 41. FIG. 4 is a perspective view of anexample coiled 24f

2×12f patch cord. Each patch cord 110 includes a 24f cable section 126terminated by a multifiber connector 130 configured to connect to activeassembly connector 41. Patch cord connector 130 and its ports (describedbelow) are thus referred to as being “active-assembly-wise.” Each patchcord 110 also includes first and second 12f cable sections 136A and 136Bterminated at respective ends by multifiber connectors 140A and 140Bconfigured to connect with fiber optic cable connectors 20A and 20B in akey-up to key-down configuration (with connectors 140A and 140B beingkey up). Patch cord connector 140 and its ports (described below) arethus referred to as being “cable-wise.” First and second 12f cablesections 136A and 136B are operably connected to first 24f cable section126 via a furcation member 150. The 24f cable section 126 carriestwenty-four fibers 36 (see inset in FIG. 3) while 12f cable sections136A and 136B each carry twelve fibers 36. In example embodiments,furcation member 150 is a rigid ferrule or a flexible tube having aboutthe same diameter as 24f cable section 126.

The fibers 36 in patch cords 110L and 110R is configured in a selectmanner so that the fiber polarity is maintained between activeassemblies 40L and 40R at the respective ends of system 100. Thetwenty-four fibers 36 in patch cords 110L and 110R constitute respectiveharnesses 112L and 112R configured for 24f

2×12f polarity-preserving interconnections. Further, patch cords 110 areconfigured so that they can be used at either end of system 100, i.e.,patch cords 110L and 110R are interchangeable so that only one type ofpatch cord is needed for system 100. Example patch cords 110 aredescribed in greater detail below. In an example embodiment, fibers 36are bend-insensitive (or alternatively “bend resistant”) fibers, asdescribed in greater detail below.

FIG. 5 is a schematic diagram of system 100, wherein active assembly 40Lincludes connector 41, such as 24f non-pinned MPO connectors, andwherein fiber optic cable 10 includes two pairs of connectors: 20AL and20BL at one end and 20AR and 20BR at the other end. In an exampleembodiment, connectors 20 are 12f pinned MPO connectors. In an exampleembodiment, connectors 20 include multifiber ferrules 21.

Active assembly connector 41L is connected to fiber optic cableconnectors 20AL and 20BL via patch cord 110L, and active assemblyconnector 41R is connected to fiber optic cable connectors 20AR and 20BRvia patch cord 110R. Patch-cord connector 130L connects to activeassembly connector 41L, and patch-cord connector 130R connects to MPOactive assembly connector 41R. Patch-cord connectors 140AL and 140BLconnect to fiber optic cable connectors 20AL and 20BL, while patch-cordconnectors 140AR and 140BR connect to fiber optic cable connectors 20ARand 20BR. In an example embodiment, active assembly connectors 41include a multifiber ferrule 43, and patch-cord connectors 130 and 140include respective multifiber ferrules 131 and 141.

Patch-cord connector 130L has ports 24NP(x_(L)) and patch-cord connector130R has ports 24NP(x_(R)), where x_(L), x_(R) denote the port numbers,for 1≦x_(L), x_(R)≦24. Likewise, fiber optic cable connectors 20AL and20BL have respective ports 12PAL(y_(AL)) and 12PBL(y_(BL)) for 1≦y_(AL),y_(BL)≦12, while fiber optic cable connectors 20AR and 20BR haverespective ports 12PAR(y_(AR)) and 12PBR(y_(BR)) for 1≦y_(AR),y_(BR)≦12. The letters “NP” and “P” in the connector reference numberscan in one example embodiment be understood to represent the case wherethe connectors having “no pins” and “pins,” respectively. Generally,however, the letters “NP” and “P” are simply used to distinguish betweenthe ports of the different connectors without regard to the pinconfiguration.

The method of establishing a suitable universal port configuration forharnesses 112 in patch cords 110 is now described with reference to FIG.5. First, an initial (fiber) connection is made in patch cord 110Lbetween any active-assembly-wise port 24NPL(x_(L)) and any cable-wiseport 12PAL(y_(AL)) or 12PBL(y_(BL)). An end-to-end pairings methodbetween active-assembly-wise ports 24NPL(x_(L)) and 24NPR(x_(R)) ofrespective patch-cord connectors 130L and 130R (which is based on aselect pairing method between transceiver ports 42L

42R, i.e., 01T

01R, 02T

02R, etc.) allows for the initial port connections to be carried throughfrom active assembly connector 41L to active assembly connector 41R,i.e., from active-assembly-wise ports 24NPL(x_(L)) of patch cord 110L tothe corresponding active-assembly-wise ports 24NPR(x_(R)) of patch cord110R.

Note that fiber optic cable 10 maps cable-wise ports 12PAL(y_(AL)) and12PBL(y_(BL)) of patch cord 110L to ports 12PAR(y_(AR)) and12PBR(y_(BR)) of patch cord 110R so that each cable-wise port in onepatch cord is connected to a corresponding cable-wise port of the otherpatch cord.

Set out in Table 1 is an example active assembly pairings method thatdefines how active-assembly-wise ports 24NPL(x_(L)) of patch-cordconnector 130L are mapped to active-assembly-wise ports 24NPR(x_(R)) ofpatch-cord connector 130R in a manner that maintains polarity based onmapping the transmit and receive transceiver ports (01T

01R, 02T

02R, etc.) between active assemblies 40L and 40R. An aspect of theassembly includes determining the pairings method if one already exists,or establishing a pairings method if one does not already exist.

TABLE 1 PAIRINGS TABLE 24NPL(x_(L)) 24NPR(x_(R)) 1 13 2 14 3 15 4 16 517 6 18 7 19 8 20 9 21 10 22 11 23 12 24 13 1 14 2 15 3 16 4 17 5 18 619 7 20 8 21 9 22 10 23 11 24 12

The pairings method can be expressed as follows:24NPL(x _(L))

24NPR(x _(R)) for 1≦x _(L)≦12 and 13≦x _(R)≦24 and24NPL(x _(L))

24NPR(x _(R)) for 13≦x _(L)≦24 and 1≦x _(R)≦12.

From the pairings method, it is seen, for example, that patch cord port24NPL(4), which is associated with active assembly port 03R of activeassembly connector 41L, is be connected to patch cord port 24NPR(16) ofactive assembly connector 41R which is associated with active assemblyport 03T (see also FIG. 4). Thus, a fiber 36 from active-assembly-wisepatch cord port 24NPL(4) that connects to cable-wise patch cord port12PBL(4) is traced from patch cord port 12PBL(4) through fiber opticcable 10 over to cable-wise patch cord port 12PBR(9) and is thenconnected by another fiber 36 to active-assembly-wise patch cord port24NPR(16). This connection pathway is then repeated in the oppositedirection from active-assembly-wise patch cord port 24NPR(4) toactive-assembly-wise patch cord port 24NPL(16) to form a correspondingconnection pathway. This process is repeated for the unused ports untilthere are no more port connections to be made. The result is a polaritypreserving universal optical connection between active assemblies 40Land 40R.

FIG. 6 shows an example configuration of harness 112 for system 100 ofFIG. 5 as established using the above-described method. The twoharnesses 112L and 112R appear to have different configurations in theschematic representation shown FIG. 5. This is due to using a2-dimensional representation to describe what is in fact a 3-dimensionalembodiment. However, one skilled in the art will understand that theharness configurations are in fact the same, so that patch cords 110Land 110R are the same and provide a universal connection for fiber opticcable 10. This is illustrated in FIG. 7, which is a perspective view ofan example harness 112 that connects multifiber patch-cord connectors130 and 140.

In the example configuration of patch cord 110L of FIG. 6, fibers 36-7through 36-12 and 36-19 through 36-24 are routed to 12f cable section136A and fibers 36-1 through 36-6 and 36-13 through 36-18 are routed to12f cable section 136B.

In an example embodiment, patch-cord connectors 140A and 140B areinstalled on respective 12f cable sections 136A and 136B with thefollowing port configurations. In cable section 136A, fibers 36-7through 36-12 are connected to patch-cord connector ports 12PAL(6)through 12PAL(1), respectively, and fibers 36-19 through 36-24 areconnected to patch-cord connector ports 12PAL(7) through 12PAL(12),respectively. Similarly, in cable section 136B, fibers 36-1 through 36-6connected to patch-cord connector ports 12PBL(1) through 12PAL(6),respectively, and fibers 36-13 through 36-18 are connected to patch-cordconnector ports 12PAL(12) through 12PAL(7), respectively. This is theconfiguration shown schematically in FIG. 6. In an example embodiment,patch-cord connectors 130, 140A and 140B are processed (e.g., polished)in accordance with the particular connector preparation techniques.

FIG. 8 is an end-on view of active-assembly-wise 24f connector 130illustrating how the connector ports 24NP can be divided up into anumber of different groups G, such as groups G1 through G4. There are atleast two ports per group G. Likewise, FIG. 9 is an end-on view ofcable-wise 12f connectors 140A and 140B illustrating how the connectorports 12PA and 12PB can be divided up into different groups G′ and G″,such as groups G1′ and G2′, and G1″ and G2″. A variety of differentgroups G, G′ and G″ are can be made, such as pairs of connector ports,as shown by groups GP and GP″ in FIG. 8. Also, two rows of six ports12PA and two rows of six ports 12PB are shown for respective connectors140A and 140B by way of illustration. Other port configurations arecontemplated herein, such as one or both connectors 140A and 140B eachhaving a single row of twelve ports.

Also, the various groups G, G′ and G″ can be combined into largergroups. For example, groups G1 and G3 of multifiber ferrule 131L can becombined to form an upper group GU, and groups G2 and G4 can be combinedto form a lower receiving area GL.

With reference to FIG. 5 through FIG. 9, an example embodiment of theinvention is fiber optic assembly 110 having a multifiber ferrule 131 atone end and two multifiber ferrules 141A and 141B at the other end.Multifiber ferrule 131 has one or more groups G of ports 24NP, whilemultifiber ferrules 141A and 141B respectively have one or more groupsG′ and G″ of ports 12PA and 12PB. Multifiber ferrule 131 is arrangedrelative to multifiber ferrules 141A and 141B such that fibers 36 canoptically connect ports 24NP to ports 12PA or 12PB. In an exampleembodiment, multifiber ferrule 131R has upper and lower groups GU and GLof twelve ports 24PL, while multifiber ferrules 141A and 141Brespectively have upper and lower groups G1′ and G2′ and G1″ and G2″ ofsix ports 12PA and six ports 12PB.

In an example embodiment, at least one group G, at least one group G′and at least one group G″ has six ports. In an example embodiment, atleast one group G, at least one group G′ and at least one group G″ hastwo ports. In an example embodiment, at least one group G has twelveports.

Groups G are said to be “directly facing” corresponding groups G′ and G″if multifiber ferrule 131 can be arranged substantially in opposition tomultifiber ferrules 141A and 141B. This may mean, for example, thatharness 112 may be flexible (e.g., part of an optical fiber cable) andthus capable of being bent such that multifiber ferrule 131 andmultifiber ferrules 141A and 141B can be placed in a number of relativeorientations, including in opposition. Thus, in some cases fibers 36 canbe connected to directly facing ports (e.g., port 24NPL(1) to 12PBL(1);see FIG. 6) without having to “flip” the fiber, i.e., without having toconnect the fiber to a non-directly facing group. In other cases, fibers36 are connected to non-directly facing ports by “flipping” the fibers(e.g., port 24NPL(7) to 12PAL(6); see FIG. 6).

In an example embodiment, ports 24NP of multifiber ferrule 131 generallyface ports 12PA and 12PB of multifiber ferrules 141A and 141B. Thevarious groups G can be aligned with each other from one ferrule to theother, with fibers 36 extending from at least two groups G of multifiberferrule 131 to at least two groups G′ and/or G″ of multifiber ferrules141A and/or 141B, thereby defining at least two groups of fibers 36 forharness 112.

In an example embodiment, fibers 36 connect at least one group G to adirectly facing group G′ or G″ without having to cross or “flip” thefibers. In addition, at least one group G is flipped as it extends togroup G′ or G″. In other embodiments, at least one of groups G isconnected directly across to an essentially directly facing group G′ orG″, but the faces of the ferrules need not be parallel to each other. Inyet other embodiments, at least one subgroup G is connected to at leastone other group G′ or G″ wherein the connecting fibers 36 are flipped,and the connected group G′ or G″ is not a directly facing group.

With reference again to FIG. 3, in an example embodiment of patch cord110, the 24f cable section 126 is a small-diameter interconnect cablecontaining twenty-four color-coded, e.g. 250 μm outside diameter, fibers36. Fibers 36 are arranged within patch-cord connector 130 (e.g., withina connector ferrule, not shown) so that when viewing patch-cordconnector 130 end on, such as shown in FIG. 10, key-up fibers 36-1through 36-12 that make up the top row and run left to right (from Blue,Orange . . . Aqua, i.e., “B→A”) while fibers 36-13 through 36-24 make upthe bottom row and also run left to right as B→A.

As mentioned above, in an example embodiment, fibers 36 for the variousoptical interconnection assemblies considered herein may comprisebend-resistant (bend insensitive) optical fibers. Such fibers areadvantageous because they preserve and provide optical performance notattainable with conventional fibers. In an example embodiment, fibers 36can be multimode fibers, for example bend-resistant fibers, whichprovide stability for higher order modes that are otherwise unstableeven for short fiber lengths. Consequently, bend-resistant fibers 36allow for bending for installation, routing, slack storage, higherdensity and the like, thereby allowing rugged installations both by thecraft and untrained individuals.

FIG. 11 shows a schematic representation of the refractive index profileof a cross-section of the glass portion of an embodiment of an exemplarymultimode, bend-resistant optical fiber 36 comprising a glass core 37and a glass cladding 42, the cladding comprising an inner annularportion 38, a depressed-index annular portion 39, and an outer annularportion 40. FIG. 12 is a schematic representation (not to scale) of across-sectional view of the optical fiber of FIG. 11. The core 37 hasouter radius R1 and maximum refractive index delta Δ1MAX. The innerannular portion 38 has width W2 and outer radius R2. Depressed-indexannular portion 39 has minimum refractive index delta percent Δ3MIN,width W3 and outer radius R3. The depressed-index annular portion 39 isshown offset, or spaced away, from the core 37 by the inner annularportion 38. The annular portion 39 surrounds and contacts the innerannular portion 38. The outer annular portion 40 surrounds and contactsthe annular portion 39. The clad layer 42 is surrounded by at least onecoating 44, which may in some embodiments comprise a low modulus primarycoating and a high modulus secondary coating.

The inner annular portion 38 has a refractive index profile Δ2(r) with amaximum relative refractive index Δ2MAX, and a minimum relativerefractive index Δ2MIN, where in some embodiments Δ2MAX=Δ2MIN. Thedepressed-index annular portion 39 has a refractive index profile Δ3(r)with a minimum relative refractive index Δ3MIN. The outer annularportion 40 has a refractive index profile Δ4(r) with a maximum relativerefractive index Δ4MAX, and a minimum relative refractive index Δ4MIN,where in some embodiments Δ4MAX=Δ4MIN. Preferably, Δ1MAX>Δ2MAX>Δ3MIN.

In some embodiments, the inner annular portion 38 has a substantiallyconstant refractive index profile, as shown in FIG. 11 with a constantΔ2(r); in some of these embodiments, Δ2(r)=0%. In some embodiments, theouter annular portion 40 has a substantially constant refractive indexprofile, as shown in FIG. 10 with a constant Δ4(r); in some of theseembodiments, Δ4(r)=0%. The core 37 has an entirely positive refractiveindex profile, where Δ1(r)>0%. R1 is defined as the radius at which therefractive index delta of the core first reaches value of 0.05%, goingradially outwardly from the centerline. Preferably, the core 37 containssubstantially no fluorine, and more preferably the core 37 contains nofluorine.

In some embodiments, the inner annular portion 38 preferably has arelative refractive index profile Δ2(r) having a maximum absolutemagnitude less than 0.05%, and Δ2MAX<0.05% and Δ2MIN>−0.05%, and thedepressed-index annular portion 39 begins where the relative refractiveindex of the cladding first reaches a value of less than −0.05%, goingradially outwardly from the centerline. In some embodiments, the outerannular portion 40 has a relative refractive index profile Δ4(r) havinga maximum absolute magnitude less than 0.05%, and Δ4MAX<0.05% andΔ4MIN>−0.05%, and the depressed-index annular portion 39 ends where therelative refractive index of the cladding first reaches a value ofgreater than −0.05%, going radially outwardly from the radius whereΔ3MIN is found.

Example optical fibers 36 considered herein are multimode and comprise agraded-index core region and a cladding region surrounding and directlyadjacent to the core region, the cladding region comprising adepressed-index annular portion comprising a depressed relativerefractive index relative to another portion of the cladding. Thedepressed-index annular portion of the cladding is preferably spacedapart from the core. Preferably, the refractive index profile of thecore has a curved shape, for one example, a generally parabolic shape.

The depressed-index annular portion may, for example, comprise a) glasscomprising a plurality of voids, or b) glass doped with one or moredowndopants such as fluorine, boron, individually or mixtures thereofThe depressed-index annular portion may have a refractive index deltaless than about −0.2% and a width of at least about 1 micron, thedepressed-index annular portion being spaced from said core by at leastabout 0.5 microns.

In some embodiments, the multimode optical fibers comprise a claddingwith voids, the voids in some preferred embodiments are non-periodicallylocated within the depressed-index annular portion. “Non-periodicallylocated” means that if one takes a cross section (such as a crosssection perpendicular to the longitudinal axis) of the optical fiber,the non-periodically disposed voids are randomly or non-periodicallydistributed across a portion of the fiber (e.g. within thedepressed-index annular region). Similar cross sections taken atdifferent points along the length of the fiber will reveal differentrandomly distributed cross-sectional hole patterns, i.e., various crosssections will have different hole patterns, wherein the distributions ofvoids and sizes of voids do not exactly match for each such crosssection. That is, the voids are non-periodic, i.e., they are notperiodically disposed within the fiber structure. These voids aredisposed (elongated) along the length (i.e. generally parallel to thelongitudinal axis) of the optical fiber, but do not necessarily extendthe entire length of the entire fiber for typical lengths oftransmission fiber. It is believed that at least some of the voidsextend along the length of the fiber a distance less than about 20meters, more preferably less than about 10 meters, even more preferablyless than about 5 meters, and in some embodiments less than 1 meter.

The multimode optical fiber disclosed herein exhibits very low bendinduced attenuation, in particular very low macrobending inducedattenuation. In some embodiments, high bandwidth is provided by lowmaximum relative refractive index in the core, and low bend losses arealso provided. Consequently, the multimode optical fiber may comprise agraded index glass core; and an inner cladding surrounding and incontact with the core, and a second cladding comprising adepressed-index annular portion surrounding the inner cladding, saiddepressed-index annular portion having a refractive index delta lessthan about −0.2% and a width of at least 1 micron, wherein the width ofsaid inner cladding is at least about 0.5 microns and the fiber furtherexhibits a 1 turn, 10 mm diameter mandrel wrap attenuation increase ofless than or equal to about 0.4 dB/turn at a wavelength of 850 nm (“850nm”), a numerical aperture (NA) of greater than 0.14, more preferablygreater than 0.17, even more preferably greater than 0.18, and mostpreferably greater than 0.185, and an overfilled bandwidth greater than1.5 GHz-km at 850 nm. By way of example, the numerical aperture for themultimode optical fiber 36 is between about 0.185 and about 0.215.

Multimode fibers 36 having a 50 micron diameter core 37 can be made toprovide (a) an overfilled (OFL) bandwidth of greater than 1.5 GHz-km,more preferably greater than 2.0 GHz-km, even more preferably greaterthan 3.0 GHz-km, and most preferably greater than 4.0 GHz-km at an 850nm wavelength. By way of example, these high bandwidths can be achievedwhile still maintaining a 1 turn, 10 mm diameter mandrel wrapattenuation increase at an 850 nm wavelength of less than 0.5 dB, morepreferably less than 0.3 dB, even more preferably less than 0.2 dB, andmost preferably less than 0.15 dB. These high bandwidths can also beachieved while also maintaining a 1 turn, 20 mm diameter mandrel wrapattenuation increase at an 850 nm wavelength of less than 0.2 dB, morepreferably less than 0.1 dB, and most preferably less than 0.05 dB, anda 1 turn, 15 mm diameter mandrel wrap attenuation increase at an 850 nmwavelength, of less than 0.2 dB, preferably less than 0.1 dB, and morepreferably less than 0.05 dB. Such fibers are further capable ofproviding a numerical aperture (NA) greater than 0.17, more preferablygreater than 0.18, and most preferably greater than 0.185. Such fibersare further simultaneously capable of exhibiting an OFL bandwidth at1300 nm which is greater than about 500 MHz-km, more preferably greaterthan about 600 MHz-km, even more preferably greater than about 700MHz-km. Such fibers are further simultaneously capable of exhibitingminimum calculated effective modal bandwidth (Min EMBc) bandwidth ofgreater than about 1.5 MHz-km, more preferably greater than about 1.8MHz-km and most preferably greater than about 2.0 MHz-km at 850 nm.

Preferably, the multimode optical fiber disclosed herein exhibits aspectral attenuation of less than 3 dB/km at 850 nm, preferably lessthan 2.5 dB/km at 850 nm, even more preferably less than 2.4 dB/km at850 nm and still more preferably less than 2.3 dB/km at 850 nm.Preferably, the multimode optical fiber disclosed herein exhibits aspectral attenuation of less than 1.0 dB/km at a wavelength of 130 nm(“1300 nm”), preferably less than 0.8 dB/km at 1300 nm, even morepreferably less than 0.6 dB/km at 1300 nm.

In some embodiments, the core extends radially outwardly from thecenterline to a radius R1, wherein 10≦R1≦40 microns, more preferably20≦R1≦40 microns. In some embodiments, 22≦R1≦34 microns. In somepreferred embodiments, the outer radius of the core is between about 22to 28 microns. In some other preferred embodiments, the outer radius ofthe core is between about 28 to 34 microns.

In some embodiments, the core has a maximum relative refractive index,less than or equal to 1.2% and greater than 0.5%, more preferablygreater than 0.8%. In other embodiments, the core has a maximum relativerefractive index, less than or equal to 1.1% and greater than 0.9%.

In some embodiments, the optical fiber exhibits a 1 turn, 10 mm diametermandrel attenuation increase of no more than 1.0 dB, preferably no morethan 0.6 dB, more preferably no more than 0.4 dB, even more preferablyno more than 0.2 dB, and still more preferably no more than 0.1 dB, atall wavelengths between 800 nm and 1400 nm. An example optical fiber 36is also disclosed in U.S. patent application Ser. No. 12/250,987 filedon Oct. 14, 2008 and Ser. No. 12/333,833 filed on Dec. 12, 2008, thedisclosures of which are incorporated herein by reference.

High-Speed Data-Rate Optical Transport System with 24f

24f Interconnections

FIG. 13 is a schematic diagram of system 100 similar to that of FIG. 3,but that utilizes a 24f fiber optic cable 10 with 24f connectors 20L and20R, and 24f single-cable patch cords 110. Each patch cord 110 isterminated at its ends with respective 24f connectors 130. Patch-cordconnector 130NP connects to active assembly connector 41, whilepatch-cord connector 130P connects to fiber optic cable connector 20.

FIG. 14 is similar to FIG. 5, but represents system 100 of FIG. 13. Theports of patch-cord connector 130NPL are denoted 24NPL(x_(L)) as above,while the ports of patch-cord connector 130PL are denoted 24PL(y_(L)),where 1≦x_(L), y_(L)≦24. Likewise, the ports of patch-cord connector130NPR are denoted 24NPR(x_(R)) as above, while the ports of patch-cordconnector 130PR are denoted 24PR(y_(R)) where 1≦x_(R), y_(R)≦24.

The method of establishing a suitable universal port configuration forharness 112 for patch cord 110 is similar to that as described above inconnection with the 24f

2×12f assemblies. With reference to FIG. 8, first, an initial opticalconnection (e.g., with an optical fiber 36) is made in patch cord 110Lbetween any active-assembly-wise patch cord port 24NPL(x_(L)) and anycable-wise patch cord port 12PL(y_(L)). The pairings method betweenpatch cord ports 24NPL(x_(L)) of patch cord 110L and patch cord ports24NPR(x_(R)) of patch cord 110R, along with the correspondence betweencable-wise ports of the patch cords via fiber optic cable 10, allows forthe initial port connection to be carried through from active assemblyconnector 41L to active assembly connector 41R.

From the pairings method as described above, it is seen for example thatactive-assembly-wise patch-cord port 24NPL(4) associated with activeassembly receive port 03R is connected to active-assembly-wisepatch-cord port 24NPR(16) associated with active assembly transmit port03T. Thus, a fiber 36 from active-assembly-wise patch-cord port 24NPL(4)that connects to cable-wise patch-cord port 12PBL(4) is traced throughfiber optic cable 10 over to cable-wise patch-cord port 12PBR(9) and isthen connected by another fiber 36 to active-assembly-wise patch-cordport 24NPR(16). This connection pathway is then repeated in the oppositedirection from active-assembly-wise patch-cord port 24NPR(4) toactive-assembly-wise patch-cord port 24NPL(16) to form a correspondingconnection pathway. This process can be repeated in partially connectingthe available ports until all desired ports are connected, or in a fullconnecting method such that all existing ports are connected. FIG. 14shows an example configuration for harnesses 112L and 112R forrespective patch cords 110L and 110R as established using this method.

FIG. 15 is a perspective view similar to FIG. 7, except for the case ofa 24f

24f optical fiber interconnection assembly 100. Note that the portconfiguration on the hidden face of connector 130NP is shown on the nearface for the sake of illustration. FIG. 16 and FIG. 17 are end-on viewsof the assembly-wise and cable-wise 24f connectors 130NP and 130P of the24f

24f optical fiber interconnection assembly 100, illustrating how theconnector ports 24NP and 24P can be respectively divided up into avariety of different groups G and G′ of two or more ports similar to thecase of the 24f

2×12f assembly described above.

Also, the various groups G and G′ can be combined into larger groups.For example, groups G1 and G3 of multifiber ferrule 131 can be combinedto form an upper group GU, and groups G2 and G4 can be combined to forma lower group GL.

With reference to FIG. 13 through FIG. 17, an example embodiment of theinvention is fiber optic assembly 110 having a multifiber ferrule 131NPat one end and a multifiber ferrule 131P at the other end. Multifiberferrule 131NP has one or more groups G of ports 24NP, while multifiberferrule has one or more groups G′ of ports 24P. Multifiber ferrule 131NPis arranged relative to multifiber ferrule 131P such that fibers 36 canoptically connector ports 24NP to ports 24P. In an example embodiment,multifiber ferrule 131NP has upper and lower groups GU and GL of twelveports 24NP, while multifiber ferrule 131P respectively has upper andlower groups GU′ and GL′ of twelve ports 24P.

In an example embodiment, at least one group G and at least one group G′has twelve ports. In another example embodiment, at least one group Gand at least one group G′ has six ports. In another example embodiment,at least one group G and at least one group G′ has two ports.

Groups G are said to be “directly facing” corresponding groups G′ ifmultifiber ferrule 131NP can be arranged substantially in opposition tomultifiber ferrules 131P. This may mean, for example, that harness 112may be flexible (e.g., part of an optical fiber cable) and thus capableof being bent such that multifiber ferrule 131NP and multifiber ferrule131P can be placed in a number of relative orientations, including inopposition. Thus, in some cases fibers 36 can be connected to directlyfacing ports (e.g., port 24NPL(6) to 24PL(7); see FIG. 14) withouthaving to “flip” the fiber, i.e., without having to connect the fiber toa non-directly facing group. In other cases, fibers 36 are connected tonon-directly facing ports by “flipping” the fibers (e.g., port 24NPL(7)to 24PL(19); see FIG. 14).

In an example embodiment, ports 24NP of multifiber ferrule 131NPgenerally face ports 24P of multifiber ferrule 131P. The various groupsG and G′ can be aligned with each other from one ferrule to the other,with fibers 36 extending from at least two groups G of multifiberferrule 131NP to at least two groups G′ of multifiber ferrule 131P,thereby defining at least two groups of fibers 36 for harness 112.

In an example embodiment, fibers 36 connect at least one group G to adirectly facing subgroup G′ without having to cross or “flip” thefibers. In addition, at least one group G is flipped as it extends togroup G′. In other embodiments, at least one of groups G is connecteddirectly across to an essentially directly facing group G′, though thefaces of the ferrules need not be parallel to each other. In yet otherembodiments, at least one group G is connected to at least one othergroup G′, wherein the connecting fibers 36 are flipped, and theconnected group G′ is not a directly facing group.

Note that for the 24f

24f assemblies 110 discussed here as well as for the case of the 24f

2×12f assemblies discussed above, correspondingly labeled groups (G1,G1′, etc.) need not directly face one another, and may not face oneanother depending on how one chooses to label the various groups for thetwo connectors. For example, with reference to FIGS. 16 and 17, thegroups for connectors 130NP and 130P are labeled in a correspondingmanner when each is viewed face on. However, when these connectors areplaced face to face, groups G1 and G3 respectively face group G3′ andG1′ along the top row, and groups G2 and G4 respectively face groups G4′and G2′ along the bottom row.

Generalized Method

FIG. 18 is a schematic diagram of a generalized 12f interconnectionsystem 200 that includes two 12f

12f assemblies 110L and 110R shown in the process of beinginterconnected with fibers 36. The 12f

12f assembly 110L includes at the active assembly end a connector 130ALwith single-fiber ports 12NPL(x_(L)), and at the fiber optic cable end aconnector 130BL with ports 12PL(y_(L)), for 1≦x_(L), y_(L)≦12. Likewise,12f

12f assembly 110R includes at the active assembly end a connector 130ARwith single-fiber ports 12NPL(x_(R)), and at the fiber optic cable end aconnector 130BR with ports 12PR(y_(R)), for 1≦x_(R), y_(R)≦12.Cable-wise patch-cord connectors 130BL and 130BR are optically connectedvia fiber optic cable 10. Active-assembly-wise single-fiber ports 12NPwithin each active-assembly-wise connector 130AL and 130AR may bepaired, i.e., {12NPL(1), 12NPL(2)}, {12NPL(3), 12NPL(4)}.

An example pairings method between active-assembly-wise ports12NPL(x_(L)) and active-assembly-wise ports 12NPR(x_(R)) based on apolarity-preserving connection between the active assemblies (not shown)is provided in the pairings table below (Table 2):

TABLE 2 Single-port pairings 12NPL(x_(L)) 12NPR(x_(R)) 1 2 2 1 3 4 4 3 56 6 5 7 8 8 7 9 10 10 9 11 12 12 11

The pairings method can be expressed as follows:12NPL(x _(L))

12NPR(x _(R)) for 1≦x _(L)≦12 ODD and 1≦x _(R)≦12 EVEN and12NPL(x _(L))

12NPR(x _(R)) for 1≦x _(L)≦12 EVEN and 1≦x _(R)≦12 ODD.

Active-assembly-wise ports 12NPL(x_(L)) and 12NPR(x_(R)) are connectedwith fibers 36 using the following rule: When in assembly 110L,active-assembly-wise port 12NPL(x_(L)) is routed to cable-wisepatch-cord port 12PL(y_(L)=n), then active-assembly-wise port12NPR(x_(R)) (as determined from the established pairings) in assembly110R is be connected (routed) to cable-wise port 12PR(y_(R)=m+1−n),where m is the total number of active assembly ports or fibers 36 (e.g.,m=12 in this example). This process is repeated for all the remainingconnector ports.

Thus, with reference to FIG. 19, active-assembly-wise assembly port12NPL(4) in assembly 110L is paired to active-assembly-wise assemblyport 12NPR(3) in assembly 110R via the given pairings method, so thaty_(L)=n=3. Active-assembly-wise assembly port 12NPL(4) is connected tocable-wise port 12PL(8) by choice, so that y_(L)=n=8. Thus,active-assembly-wise port 12NPR(y=3) in assembly 11OR is connected tocable-wise port 12PR(y_(R)=12+1−8)=12PR(5), as shown. Likewise,active-assembly-wise port 12NPL(3) in assembly 110R is paired toactive-assembly-wise port 12NPR(4) in assembly 110L. Thus,active-assembly-wise port 12NPL(3) is connected to cable-wise port12PL(7) by choice, so that y_(L)=n=7. Thus, active-assembly-wise port12NPR(4) is connected to cable-wise port 12PR(y_(R)=12+1−7)=12PR(6), asshown.

The above interconnection method has been described in connection with a12f interconnection system for the sake of illustration. One skilled inthe art will appreciate that the method applies in principle tointerconnection systems and interconnection assemblies that use anyreasonable number m of fibers.

Thus, in the general case of active-assembly-wise assembly portsmNPL(x_(L)) and mNPR(x_(R)), where m is an even number of ports (i.e.,m=12 or 24 in the above examples), the pairings method is generallyexpressed as:mNPL(x _(L))

mNPR(x _(R)) for 1≦x _(L) ≦m ODD and 1≦x _(R) ≦m EVEN andmNPL(x _(L))

mNPR(x _(R)) for 1≦x _(L) ≦m EVEN and 1≦x _(R) ≦m ODD.24f Universal Module with Single-Fiber Ports

FIG. 19 is a schematic diagram of a high-speed data-rate opticaltransport system 100 that includes two 24f

24f optical interconnection assemblies 110 and active assemblies 40having single-fiber ports 24. In an example embodiment, the two opticalinterconnection assemblies 110 include a modular enclosure called a“breakout module.” Optical interconnection assemblies 110 are connectedby a 24f fiber optic cable 10. Optical interconnection assemblies 110Land 110R respectively include a set of twenty-four active-assembly-wisesingle-fiber ports 24L(x_(L)) and 24R(x_(R)) that are mapped to (i.e.,correspond to) each other via the pairings method as set out in Table 3below:

TABLE 3 PAIRINGS TABLE 24L(x_(L)) 24R(x_(R)) 1 2 2 1 3 4 4 3 5 6 6 5 7 88 7 9 9 10 10 11 12 12 11 13 14 14 13 15 16 16 15 17 18 18 17 19 20 2019 21 22 22 21 23 24 24 23

The above pairings method can also be expressed as follows:24L(x _(L))

24R(x _(R)) for 1≦x _(L)≦24 ODD and 1≦x _(R)≦24 EVEN and24L(x _(L))

24R(x _(R)) for 1≦x _(L)≦24 EVEN and 1≦x _(R)≦24 ODD.

The same general interconnection method as described above forconfiguring the harnesses 112 of the 24f patch cords 110 is used here toconfigure harnesses 112L and 112R in optical interconnection assemblies110. First, an initial (fiber) connection is made in opticalinterconnection assembly 110L between any single-fiberactive-assembly-wise port 24L(x_(L)) and any cable-wise port24PL(y_(L)). From the pairings method it is seen, for example, thatactive-assembly-wise single-fiber port 24L(4) associated with activeassembly receive port 03R in assembly 110L is be connected toactive-assembly-wise port 24R(3) associated with active assemblytransmit port 03T in assembly 110R. Thus, a fiber 36 fromactive-assembly-wise port 24L(7) that connects to cable-wise port24PL(1) in assembly 110L is traced through fiber optic cable 10 over tooptical interconnection assembly 110R and cable-wise port 24PR(12). Thiscable-wise port is then connected by another fiber 36 toactive-assembly-wise port 24NPR(8) in optical interconnection assembly110R.

Note that the optical connection is from transmit port 03T to receiveport 03R in respective active assembly connectors 41L and 41R so thatthe polarity of the connection is preserved. This connection pathway isthen repeated in the opposite direction from active-assembly-wise port24R(7) in optical interconnection assembly 110R to active-assembly-wiseport 24L(8) in optical interconnection assembly 110L, thereby connectingtransmit port 03T of active assembly connector 41R to receive port 03Rof active assembly connector 41L.

This method is repeated for the unused ports until there are no moreport connections to be made. FIG. 19 shows example configurations forcompleted harnesses 112L and 112R in respective optical interconnectionassemblies 110 established using this iterative approach.

FIG. 20 is a perspective view of an example modular 24f

2×12f optical interconnection assembly 110. Assembly 110 includes ahousing 220 having first and second ends 222 and 224 and that defines aninterior 230. Housing 220 may be made of metal, such comprise astamped-formed metal box. Housing first end 222 includesactive-assembly-wise 24f connector 130R with ports 24NPR, and housingsecond end 224 includes cable-wise connectors 140AR and 140BR.Connectors 140AR and 140BR are connected to connector 130R by fibers 36that span housing interior 230 and that are configured using the methodsdescribed above.

The disclosure in other embodiments includes a fiber optic assembly withmultifiber connectors each having a multifiber ferrule disposed thereinso that the assembly has first and second multifiber ferrules. A groupof ports is optically connected without flipping the optical fibers, anda group of ports is optically connected by flipping the optical fibers.The ports are each arranged in rows formed in each ferrule, with therows being generally parallel to each other, such that each ferrule hasa row being a lower row and a row being an upper row. See for exampleFIGS. 7-9 and FIGS. 15-17 and the disclosure relating thereto. At leastone group of ports is optically connected by flipping the optical fibershaving a first group of flipped optical fibers. The assembly can furtherhave a second group of flipped optical fibers extending from thetermination side of the first ferrule to the termination side of thesecond ferrule. The first and second groups of flipped optical fiberscross each other as the groups extend from the first ferrule to thesecond ferrule. The at least one group of ports that is opticallyconnected without flipping the optical fibers can be located on a lowerrow of the first ferrule, and the group of ports that is opticallyconnected by flipping the optical fibers can be located on an upper rowof the first ferrule. The group of ports that is optically connectedwithout flipping the optical fibers can be located on an upper row ofthe first ferrule, and the at least one group of ports that areoptically connected by flipping the optical fibers can be located on anlower row of the first ferrule. The group of ports that are opticallyconnected without flipping the optical fibers and the group of portsthat are optically connected by flipping the optical fibers can belocated on one of the same rows of a ferrule or different rows of aferrule. Other combinations within the disclosure of the presentinvention are possible as well.

The present disclosure has been described with reference to theforegoing embodiments, which embodiments are intended to be illustrativeof the present inventive concepts rather than limiting. Persons ofordinary skill in the art will appreciate that variations andmodifications of the foregoing embodiments may be made without departingfrom the scope of the appended claims.

1. A fiber optic assembly for a high-speed data-rate optical transportsystem, comprising: a) at least first and second multifiber ferrules,each multifiber ferrule having a mating face for mating to anothermating face of an optical connector, and a termination side forreceiving optical fibers, each ferrule having a plurality of opticalfiber receiving areas being arranged in at least first and second groupsof two or more fiber receiving areas; b) the fiber receiving areas ofeach ferrule comprising fiber receiving holes formed in each ferrule,the holes extending from the mating face to the termination face so thateach of the holes are associated with the at least first and secondgroups, and respective ends of the optical fibers being opticallysecured in at least some of the holes of each of the first and secondgroups, the fibers extending thereby forming respective groups ofoptical fibers optically interconnecting the fiber receiving areas fromthe termination side of the first ferrule to the termination side of thesecond ferrule; c) some of the optical fibers extending from the firstferrule to the second ferrule in a direct orientation so that the fiberreceiving areas of each ferrule are optically interconnected withoutflipping the fibers; and d) some of the optical fibers extending fromthe first ferrule to the second ferrule such that the optical fibers areflipped so that the orientation of the ends of the optical fibers isreversed as the fibers extend from the first ferrule to the secondferrule.
 2. The fiber optic assembly of claim 1, wherein the terminationsides of the ferrules are arranged substantially in facing opposition toeach other so that some of the groups of optical fibers are essentiallyfacing groups of fiber receiving areas, and wherein the optical fibersthat are flipped are not directly facing groups.
 3. The fiber opticassembly of claim 1, wherein at least one of the first and second groupscomprises a row of fiber receiving areas.
 4. The fiber optic assembly ofclaim 1, wherein at least one of the first groups and at least one ofthe second groups respectively comprise two fiber receiving areas. 5.The fiber optic assembly of claim 1, wherein at least one of the firstgroups and at least one of the second groups respectively comprise sixfiber receiving areas.
 6. The fiber optic assembly of claim 1, whereinat least one of the first groups and at least one of the second groupsrespectively comprise twelve fiber receiving areas.
 7. The fiber opticassembly of claim 1, wherein transmit and receive pairs of fiberreceiving areas are associated with channels of the high-speed data-rateoptical transport system, wherein the channels have a corresponding datarate, and wherein the fiber optic assembly supports a data ratecorresponding to the channel data rate multiplied by the number of pairsof fiber receiving areas in the first group.
 8. The fiber optic assemblyof claim 7, wherein the channel data rate is about 10 gigabits/s.
 9. Thefiber optic assembly of claim 8, wherein the number of transmit andreceive pairs of fiber receiving areas in the first group is twelve. 10.The fiber optic assembly of claim 9, wherein ten of the twelve transmitand receive pairs of fiber receiving areas are used so as to supportabout a 100 gigabit/s data rate.
 11. The fiber optic assembly of claim1, wherein the fibers comprise bend-insensitive fibers.
 12. The fiberoptic assembly of claim 1, comprising: a third multifiber ferrule havinga plurality of fiber receiving areas that are dividable into thirdgroups of two or more fiber receiving areas; and wherein the fiberreceiving areas of the first group are connected to fiber receivingareas of both or either of the second and third groups without flippingthe fibers, and wherein the fiber receiving areas of the first group areconnected with both or either of the second and third groups by flippingthe fibers.
 13. The fiber optic assembly of claim 12, wherein the firstmultifiber ferrule has a total of twenty-four fiber receiving areas, andthe second and third multifiber ferrules each have a total of twelvefiber receiving areas.
 14. The fiber optic assembly of claim 12, whereinthe first, second and third multifiber ferrules are optically connectedto respective first, second and third active assemblies.
 15. The fiberoptic assembly of claim 1, wherein the plurality of optical fibers arecontained in one of an optical fiber cable and a modular housing. 16.The fiber optic assembly of claim 1, wherein the first and secondmultifiber ferrules are optically connected to respective first andsecond active assemblies.
 17. A fiber optic assembly for a high-speeddata-rate optical transport system having active assemblies each withtransmit and receive ports, comprising: at least first and secondmultifiber connectors each having respective pluralities of first andsecond ports that define respective pluralities of at least first andsecond groups of at least two ports each, wherein the first and secondmultifiber connectors are capable of being disposed so that the at leastfirst and second groups of ports are located on respective terminationsides of each ferrule; and a plurality of optical fibers that connectthe first and second ports according to a pairings method that maintainspolarity between the transmit and receive ports of the activeassemblies, wherein at least one of the first and second groups areoptically connected without flipping the fibers, and wherein at leastone of the first and second groups are optically connected by flippingthe fibers.
 18. The fiber optic assembly of claim 17, wherein at leastone of the first groups and at least one of the second groups includesix ports.
 19. The fiber optic assembly of claim 17, wherein at leastone of the first groups and at least one of the second groups includetwelve ports.
 20. The fiber optic assembly of claim 17, wherein thefirst and second multifiber connectors each support a total oftwenty-four ports.
 21. The fiber optic assembly of claim 17, furtherincluding: a third multifiber connector having a plurality of thirdports that define a plurality of third groups of at least two portseach, and wherein the first groups of ports face the second and thirdgroups of ports.
 22. The fiber optic assembly of claim 21, wherein thefirst multifiber connector supports twenty-four ports, and wherein thesecond and third multifiber connectors each supports twelve ports. 23.The fiber optic assembly of claim 17, wherein pairs of connector portsare associated with respective channels of the high-speed data-rateoptical transport system, wherein the channels have a corresponding datarate, and wherein the fiber optic assembly supports a data ratecorresponding to the channel data rate multiplied by the number of pairsof fiber ports in the first group.
 24. The fiber optic assembly of claim23, wherein the channel data rate is about 10 gigabits/s.
 25. The fiberoptic assembly of claim 24, wherein the number of pairs of ports in thefirst group is twelve.
 26. The fiber optic assembly of claim 25, whereinten of the twelve ports are used so as to support about a 100 gigabit/sdata rate.
 27. The fiber optic assembly of claim 17, wherein the fiberscomprise bend-insensitive fibers.
 28. The fiber optic assembly of claim17, wherein the fibers are contained in an optical fiber cable.
 29. Thefiber optic assembly of claim 17, wherein the at least one first groupand at least one second group respectively include an entire row ofports.
 30. The fiber optic assembly of claim 17 wherein, a) eachconnector comprises at least one multifiber ferrule disposed therein sothat the assembly comprises first and second multifiber ferrules; b) theat least one group of ports being optically connected without flippingthe optical fibers, and the at least one group of ports being opticallyconnected by flipping the optical fibers, are each arranged in rowsformed in each ferrule, the rows being generally parallel to each other,such that each ferrule has a row being a lower row and a row being anupper row; c) the at least one group of ports being optically connectedwithout flipping the optical fibers is located on a lower row of thefirst ferrule, and d) the at least one group of ports being opticallyconnected by flipping the optical fibers is located on an upper row ofthe first ferrule.
 31. The fiber optic assembly of claim 17 wherein, a)each connector comprises at least one multifiber ferrule disposedtherein so that the assembly comprises first and second multifiberferrules; b) the at least one group of ports being optically connectedwithout flipping the optical fibers, and the at least one group of portsbeing optically connected by flipping the optical fibers, are eacharranged in rows formed in each ferrule, the rows being generallyparallel to each other, such that each ferrule has a row being a lowerrow and a row being an upper row; c) the at least one group of portsbeing optically connected without flipping the optical fibers is locatedon an upper row of the first ferrule, and d) the at least one group ofports being optically connected by flipping the optical fibers islocated on a lower row of the first ferrule.
 32. The fiber opticassembly of claim 17 wherein, a) each connector comprises at least onemultifiber ferrule disposed therein so that the assembly comprises firstand second multifiber ferrules; b) the at least one group of ports beingoptically connected without flipping the optical fibers, and the atleast one group of ports being optically connected by flipping theoptical fibers, are each arranged in rows formed in each ferrule, therows being generally parallel to each other, such that each ferrule hasa row being a lower row and a row being an upper row; and c) the atleast one group of ports being optically connected without flipping theoptical fibers and the at least one group of ports being opticallyconnected by flipping the optical fibers are located on the same row ofthe first ferrule.
 33. The fiber optic assembly of claim 17 wherein, a)each connector comprises at least one multifiber ferrule disposedtherein so that the assembly comprises first and second multifiberferrules; b) the at least one group of ports being optically connectedwithout flipping the optical fibers, and the at least one group of portsbeing optically connected by flipping the optical fibers, are eacharranged in rows formed in each ferrule, the rows being generallyparallel to each other, such that each ferrule has a row being a lowerrow and a row being an upper row; and c) the at least one group of portsbeing optically connected without flipping the optical fibers and the atleast one group of ports being optically connected by flipping theoptical fibers are located on different rows of the first ferrule. 34.The fiber optic assembly of claim 17 wherein, a) each connectorcomprises at least one multifiber ferrule disposed therein so that theassembly comprises first and second multifiber ferrules; b) the at leastone group of ports being optically connected without flipping theoptical fibers, and the at least one group of ports being opticallyconnected by flipping the optical fibers, are each arranged in rowsformed in each ferrule, the rows being generally parallel to each other,such that each ferrule has a row being a lower row and a row being anupper row; and c) the at least one group of ports being opticallyconnected without flipping the optical fibers extend from a lower row ofthe first ferrule to a lower row of the second ferrule.
 35. The fiberoptic assembly of claim 17 wherein, a) each connector comprises at leastone multifiber ferrule disposed therein so that the assembly comprisesfirst and second multifiber ferrules; b) the at least one group of portsbeing optically connected without flipping the optical fibers, and theat least one group of ports being optically connected by flipping theoptical fibers, are each arranged in rows formed in each ferrule, therows being generally parallel to each other, such that each ferrule hasa row being a lower row and a row being an upper row; and c) the atleast one group of ports being optically connected by flipping theoptical fibers extend from a lower row of the first ferrule to an upperrow of the second ferrule.
 36. The fiber optic assembly of claim 17wherein, a) each connector comprises at least one multifiber ferruledisposed therein so that the assembly comprises first and secondmultifiber ferrules; b) the at least one group of ports being opticallyconnected without flipping the optical fibers, and the at least onegroup of ports being optically connected by flipping the optical fibers,are each arranged in rows formed in each ferrule, the rows beinggenerally parallel to each other, such that each ferrule has a row beinga lower row and a row being an upper row; c) the at least one group ofports being optically connected by flipping the optical fiberscomprising a first group of flipped optical fibers; d) the assemblyfurther comprising a second group of flipped optical fibers extendingfrom the termination side of the first ferrule to the termination sideof the second ferrule; and e) wherein the first and second groups offlipped optical fibers cross each other as the groups extend from thefirst ferrule to the second ferrule.